Area Forecast Discussion
Issued by NWS Honolulu, HI
Issued by NWS Honolulu, HI
671 FXHW60 PHFO 061337 AFDHFO Area Forecast Discussion National Weather Service Honolulu HI 337 AM HST Mon May 6 2024 .SYNOPSIS... Breezy easterly trade winds will continue through the morning hours, decreasing to moderate levels by this afternoon. A passing weak upper level disturbance will drift over the islands today enhancing passing showers with a few thunderstorms possible over the Big Island. An unstable band of clouds and showers will drift into the islands on the trade winds, bringing another round of wet weather for all islands from Wednesday into Thursday. An upper trough moving into the region from the north will keep wet weather in the forecast lasting into the weekend. && .DISCUSSION... Local island radar imagery shows numerous showers riding into the windward and mountain slopes of all islands this morning. Some of the stronger showers are drifting over drier leeward areas. Satellite water vapor channel imagery continues to show a weakening upper level low slowly drifting from west to east across the island chain. This upper low will produce enough instability to keep wet trade winds in the forecast today with isolated thunderstorms over the Big Island as it tracks eastward across the state. A 1030 mb high pressure system remains far north of the island chain and will continue to produce breezy easterly trade winds across the state through the morning hours. By this afternoon we will transition to more moderate wind speeds as the high pressure system drifts eastward away from the Hawaiian Islands. Expect light to moderate easterly trade winds to continue through the rest of the week with a hybrid wind pattern of trade wind and sea breezes over terrain sheltered leeward areas. Wetter than normal conditions remain in the forecast for all islands through much of this week. Enhanced showers will continue into Monday as a weakening upper level disturbance drifts from west to east across the island chain. Tuesday will trend a bit drier. An unstable band of clouds and showers, remnants of an old East Pacific cold front, will drift into the islands on the trade winds producing wet weather for all islands from Wednesday into Thursday. An upper level trough sweeping in from north on Thursday and Friday will likely keep enhanced showers in the forecast into next weekend. && .AVIATION... Breezy easterly trade winds will persist today, with clouds and showers favoring windward and mauka locations. MVFR conditions will be possible in showers, especially across windward areas overnight through the early morning hours. VFR conditions will prevail elsewhere. Although confidence is low, added instability associated with an upper low in the area could lead to an isolated thunderstorm over the Big Island this afternoon. AIRMET Sierra for tempo mountain obscuration will persist over windward portions of each island through the morning hours. AIRMET Tango is in effect for moderate turbulence below 8000 feet downwind of island terrain due to the winds. Additionally, moderate turbulence aloft (FL280-FL380) is expected today. && .MARINE... A high pressure system north of the state has shifted east overnight easing the fresh to strong breezes over some zones. Thus the Small Craft Advisory (SCA) for all waters has been scaled back to typically windy waters around the Big Island and Maui County through today. SCA conditions may drop late Tuesday into Wednesday as the high continues to track east and weaken. Expect gentle to locally fresh trade winds to prevail Wednesday through Friday as a trough develops north of the state and lingers. In addition, a few heavy showers will be possible today. Pulses of south to southwest swell are due this week, with High Surf Advisory (HSA) conditions expected by Thursday. The PacIOOS buoy off of Lanai is still showing some inconsistent energy in the 16 to 18 second range so have keep surf numbers elevated this morning but with a gradually down trend later today through Wednesday. Forerunners from a larger and longer lived south- southwest swell will arrive Wednesday, and surf is expected rise to the HSA level during the peak of the swell Thursday and Friday. A pair of small northwest swells will move through over the next several days. The Hanalei PacIOOS buoy shows some northwest energy in the 14 to 18 second range filling in early this morning. Expect this swell to continue to spread down the island chain today, peaking Tuesday, and declining late Tuesday and Wednesday. Wind- driven waves of 8 to 9 feet at 9 seconds will maintain rough east shore surf above the May average through today. As trade winds decline over the next few days, these seas will gradually decline to around May average by Tuesday, then drop to below average for the rest of the week. && .HFO WATCHES/WARNINGS/ADVISORIES... Small Craft Advisory until 6 AM HST early this morning for Kauai Northwest Waters-Kauai Windward Waters-Kauai Leeward Waters- Kauai Channel-Oahu Windward Waters-Oahu Leeward Waters-Kaiwi Channel-Maui County Windward Waters-Maui County Leeward Waters- Big Island Windward Waters. Small Craft Advisory until 6 AM HST Tuesday for Maalaea Bay- Pailolo Channel-Alenuihaha Channel-Big Island Leeward Waters-Big Island Southeast Waters. && $$ DISCUSSION...Bohlin AVIATION...Gibbs MARINE...Almanza